Here is an optical illusion of motion and color perception, which can reveal if you have normal psychological concentration.
This psychological picture test shows the amazing ability of the human brain, and perhaps, after a successful outcome of the test, it will make you wonder if we perceive the world correctly or maybe our brain deceives us. What if what we see around us is a kind of illusion of perception?
Look at the picture below, and you will see the pink circles move clockwise and disappear one after the other, creating an illusion of the movement of the gray hole between them. If you concentrate your mind in the middle of the circle on the black cross, then you will see that the moving gray hole will change its color to green. And then, as you continue to look at the cross for 10-15 seconds, all the pink circles will disappear and there will be only one green circle that will keep moving in the same direction. If you manage to see all the pink circles disappear and only one green circle move, then you have normal psychological concentration.